According to kinetic theory of gases, the incorrect statement is

Options

A. Collisions of gas molecules are perfectly elastic
B. Particle of gas moves in all possible directions in straight line
C. Gas molecules are considered as point masses
D. At a particular tamperature all molecules have same kinetic energy

Answer

To determine the incorrect statement according to the kinetic theory of gases, we will analyze each statement based on the principles of the kinetic theory.

### Step-by-Step Solution:

1. **Understanding the Kinetic Theory of Gases**:
The kinetic theory of gases provides a model that explains the behavior of gases in terms of particles in motion. It is based on several postulates.

2. **Analyzing Each Statement**:
- **Statement 1**: "Collisions of gas molecules are perfectly elastic."
- **Explanation**: This statement is correct. In an elastic collision, there is no net loss of kinetic energy in the system.

- **Statement 2**: "The volume of particles is negligible with respect to the volume of the container."
- **Explanation**: This statement is also correct. The actual volume occupied by gas particles is much smaller than the volume of the container they are in.

- **Statement 3**: "All the molecules have the same average kinetic energy."
- **Explanation**: This statement is incorrect. While gas molecules at a given temperature have the same average kinetic energy, individual molecules can have different kinetic energies. Thus, they do not all have the same kinetic energy.

- **Statement 4**: "They move randomly."
- **Explanation**: This statement is correct. Gas molecules move in all possible directions and at various speeds.

3. **Identifying the Incorrect Statement**:
After analyzing the statements, we find that the third statement, "All the molecules have the same average kinetic energy," is incorrect. Therefore, the answer is option 3.

### Final Answer:
The incorrect statement according to the kinetic theory of gases is: "All the molecules have the same average kinetic energy."

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